ZnO thin film deposition using colliding plasma plumes and single plasma plume: Structural and optical properties

Abstract

We report the comparative study on synthesis of thin films of ZnO on glass substrates using IR laser ablated colliding plasma plumes and conventional pulsed laser deposition using 355 nm in oxygen ambient. The optical properties of deposited films are characterized using optical transmission in the UV-visible range of spectrum and photoluminescence measurements. X-ray diffraction and atomic force microscopy are used to investigate the surface morphology of synthesized ZnO films. The films synthesized using colliding plumes created with 1064 nm are non-polar a-plane ZnO with transmission in UV-visible (300–800 nm) region ∼60% compared to polycrystalline thin film deposited using single plume which has chunk deposition and poor optical response. However, deposition with 355 nm single plume shows polar c-axis oriented thin film with average roughness (∼thickness) of ∼86 nm (∼850 nm) compared to ∼2 nm (∼3 μm) for 1064 nm colliding plumes. These observed differences in the quality and properties of thin films are attributed to the flux of mono-energetic plasma species with almost uniform kinetic energy and higher thermal velocity reaching the substrate from interaction/stagnation zone of colliding plasma plumes.